After reaching an altitude of about 17 kilometers, the rising and drying air hits the stratosphere, which acts kind of like a ceiling, causing the warm air to spread out and separate — some goes north, some south.

当海拔达到 17 千米后，上升的暖空气遇到平流层，就像遇到天花板，使暖空气分散，一些涌向北方，一些涌向南方。